ETH Gas Fees Question

I want to buy a couple of NFTs on openseas to gift as a Christmas present to someone and use it as a learning opportunity. Im planning on buying pretty worthless NFTs but the gift is a novelty thing, not a real investment (myself and the gift receiver expect this to be worth nothing). The problem I have is that I’ve never exchanged ETH before so I wanted to ask some questions on gas and fees and ask how much ETH I should buy on binance to make sure I have enough to actually buy the NFT and not be left with a bunch of excess ETH sitting in metamask or not have enough in metamask to buy the NFT.

How much total ETH would you recommend I initiall exchange assuming the following? 1. Buy ETH on binance 2. Binance to metamask would is a 0.02ETH fee + gas 3. Buy 2 0.005ETH NFT on openseas with metamask wallet would be just a gas fee (I think?)